Medial Septal Microinfusion of Scopolamine Disrupts Hippocampal Activity and Trace Jaw Movement Conditioning

• Published in: Behavioral neuroscience 2000-12, Vol.114 (6), p.1068-1077
• Main Authors: Asaka, Yukiko, Seager, Matthew A, Griffin, Amy L, Berry, Stephen D
• Format: Article
• Language: English
• Subjects: Anatomy & physiology; Animal; Animals; Behavioral psychophysiology; Behavioral sciences; Biological and medical sciences; Brain Mapping; Cerebral Cortex - drug effects; Classical Conditioning; Conditioned Responses; Conditioning, Classical - drug effects; Fundamental and applied biological sciences. Psychology; Hippocampus; Hippocampus - drug effects; Mastication - drug effects; Neural Pathways - drug effects; Neurology; Neurophysiology; Neurotransmission and behavior; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Pyramidal Cells - drug effects; Rabbits; Scopolamine; Scopolamine - pharmacology; Septal Nuclei; Septal Nuclei - drug effects; Septum Pellucidum - drug effects; Synaptic Transmission - drug effects; Theta Rhythm
• ISSN: 0735-7044; 1939-0084
• DOI: 10.1037/0735-7044.114.6.1068

This study investigated the effects of microinfusion of scopolamine into the medial septum (MS Scp) on hippocampal neurophysiology and learning of the rabbit's classically conditioned jaw movement response. The percentage of hippocampal theta slow waves (2-8 Hz) decreased after drug infusion in the MS Scp group but did not change in control groups that received infusion of saline into the MS or scopolamine into the cortex. Unit recordings from the MS Scp group showed significantly smaller conditioning-related hippocampal neural responses than seen in controls, and during conditioning, rabbits in the MS Scp group took significantly longer to reach learning criterion than either control group. Thus, the neural and behavioral impairments previously reported for systemic muscarinic blockade were reproduced by microinfusions restricted to the medial septal nucleus.